This invention is directed to thermoplastic compositions comprising aromatic polycarbonate, their method of manufacture, and method of use thereof, and in particular impact-modified thermoplastic polycarbonate compositions having low gloss and a good balance of physical properties.
Thermoplastics having a low gloss finish are useful in the manufacture of articles and components for a wide range of applications, from automobile components, to decorative articles, to housings for electronic appliances, such as computers. A low gloss finish for a plastic article can be obtained using different methods. Mechanically texturing a plastic surface has long been used, but this type of surface finish is prone to wear and ultimately increases in gloss with use. Further, mechanical texturing adds processing steps and increases manufacturing costs. Modifications to the moldable thermoplastic composition itself is therefore desirable, whereupon an article can have a low gloss surface immediately after processes such as molding, casting, extruding, or rolling of a suitable low gloss composition. Excellent mechanical properties are also desired in a low gloss thermoplastic composition for use in these applications.
Polycarbonates, which have excellent mechanical properties, can be used in applications as described above. Low gloss finishes for polycarbonates can be attained by adding gloss-reducing fillers and additives such as particulate silica, or resins with gloss reducing functionality; however the usefulness of such blends can be mitigated by reduction in or loss of mechanical properties such as, for example, impact strength and ductility retention.
There accordingly remains a need in the art for low gloss thermoplastic compositions comprising polycarbonates, as well as impact modified polycarbonates.
Desirable features of such materials include both excellent mechanical properties and ease of manufacture. The mechanical properties of the low gloss thermoplastic composition are desirably comparable to, or better than, those of high gloss polycarbonate.